The invention concerns a device for constructing a thread reserve wound with parallel turns onto a bobbin. When a thread reserve is wound with parallel turns, it is generally axially displaced from the standard bobbin winding. The standard technique in this case can be either high-precision or regular cross winding. A reserve is often constructed at the commencement of a bobbin trip (winding), when it will subsequently be necessary for example to tie the tail end of a foregoing bobbin to the leading end of a succeeding bobbin. It is, on the other hand, also possible to construct the reserve for a period of time at any instant during a bobbin trip, when for example defective thread is to be separated from regular thread.
German OS 2 328 828 discloses a device of the aforesaid type that constructs a thread reserve on a bobbin in a winder. The reserve is axially displaced in relation to the standard winding. This device employs a reserve shackle in the form of a surface with a thread-channeling edge that extends perpendicular to the bobbin axis. The purpose of this device is to wind the thread at the commencement of a winding process onto a reserve section that is axially displaced in relation to the standard winding. The reserve shackle also has a trailing edge followed by two sections that slope in opposite directions toward the axis of the bobbin and meet in a transition that is not recessed. To terminate the construction of a thread reserve at the commencement of a winding process, the reserve shackle is advanced by one drive mechanism perpendicular to the axis of the bobbin to allow the thread to cross the trailing edge and enter the adjacent area, where it can be intercepted by the traversing-thread guide, which initiates the standard winding process with the thread being distributed by the traversing-thread guide. Toward the end of the winding process another thread reserve can be wound onto the full bobbin and will accordingly not be axially displaced in relation to the standard winding. The two sections of the reserve shackle, which extend across the width of the winding, are pivoted for this purpose to where the thread is exiting, lifting it out of the traversing-thread guide and, due to the slope between the two sections, feeding it into the transition between them. Since the reserve shackle can now be moved toward and away from the axis of the bobbin to an extent that begins and ends within the width of the standard winding, the second thread reserve will occur toward the end of the winding process on the standard-wound bobbin. It is impossible to use this known device to wind another axially displaced thread reserve at any point of time during the winding process, especially not toward the end of a bobbin trip. Quite aside from the fact that the axial travel of the reserve shackle does not extend beyond the standard winding, the transition between the two sections does not constitute a stamped-out displacement eye in the actual sense and is accordingly incapable of retracting the thread over the forward wall once an axially displaced thread reserve has been constructed on a bobbin with an already considerable diameter, which would, however, be prerequisite for the traversing-thread guide to finally be able to intercept the thread.